The present invention relates to a solar cell module and to a method for the production thereof. Solar cell modules of this type are used in particular in the field of concentrating solar technology.
In photovoltaics, a plurality of solar cells are combined together to form larger modules. Within one module, a plurality of solar cells are wired up together, the module takes over further tasks in addition, such as e.g. protection of the generally very sensitive cells from weathering effects.
A special field of photovoltaics is so-called “concentrator photovoltaics” in which sunlight is concentrated by an optical system (e.g. lens, mirror) and the concentrated light beam impinges—according to the type of plant—on a relatively small solar cell.
For this purpose, the cell must be positioned exactly in the focus of the lens. Due to the small size of the cells, frequently special contacting methods (e.g. bonding) are necessary in order to contact the cells. These methods are however frequently unsuitable also for wiring up the different cells in the module. For this purpose, further contacting steps are then necessary.
In concentrator photovoltaics, solar radiation is focused by lenses. By this very high energy densities are achieved on very small areas. Thus, solar energy at a multiple of 500 is achieved for example on a circle of 2 mm diameter. The radiation distribution hereby has a Gaussian distribution, as a result of which solar radiation which is concentrated by over a multiple of 2,000 appears in the centre of the focal spot (a region of approx. 0.3 mm diameter). Thus the solar cell must be mounted in direct contact with a heat sink. In order to prevent the formation of hot spots, the most important task of this heat sink is firstly the distribution of the corresponding lost energy in the lateral direction, i.e. in width, and also at the same time of course transmission to the underlying layers. In order to achieve this, the rear side of the solar cell is therefore connected, in prior art, to a metallic layer. In addition, the upper side of the solar cell must be contacted as second electrical terminal. This contacting is thereby undertaken by means of the same metallic layer which also produces the contacting of the solar cell underside. This layer must therefore be structured in various electrically (and hence also mechanically and thermally) separated regions. This takes place by removing copper in specific regions so that regions which are electrically insulated from each other are produced.
FIG. 1 shows a solar cell according to the state of the art. This has a substrate (module base, glass carrier) 1 on which a copper plate 3a is applied by means of an adhesive layer 2a. A solar cell 5a is placed on this copper plate by means of an electrically conductive adhesive layer 4a. By means of the electrically conductive contacting of the solar cell 5a with the copper plate 3a, the solar cell is contacted on its rear side contact, here its positive terminal. Offset laterally relative to the solar cell 5a, there is disposed an insulating layer 6 which can for example consist of a glass fibre composite material. This insulating layer 6 has an electrically conductive gold layer 7 on its side orientated away from the substrate 1. The gold layer 7 is wired up electrically via a bonding wire 9 to a contact 11a as negative terminal of the solar cell.
In FIG. 1 in addition to the previously described arrangement of a solar cell which is laterally offset on the substrate, a second solar cell 5b is disposed in a corresponding manner. For serial wiring up of the two solar cells 5a and 5b, the gold layer 7 is wired up electrically to the copper layer 3b of the solar cell 5b via a connection 8b. 
In order to produce a solar cell of this type, individually fitted copper plates 3a, 3b (so-called solar cell chips) are now mounted individually on the base plate 1 via an adhesive connection 2a. The solar cell 5a or 5b respectively must thereby be placed exactly so that the centre of the solar cell is located in the focal point of the lens fitted thereabove. The electrical connection 8b between the individual cells is effected only thereafter by soldering e.g. of a silver strip 8b. It is disadvantageous in this respect that a large number of individual parts is required, for which costs accrue in the supply and in the mounting and manufacturing logistics. During the assembly, a large number of different operating steps take place, such as for example preparation of the individual surfaces, application of joining materials, such as adhesives and solder, gripping and positioning the individual parts, curing the adhesive layers and also diverse soldering processes. In addition there are also process-associated steps. This large number of operating steps increases the cycle times and lowers the throughput of a manufacturing line for solar cell modules in concentrator photovoltaics. The material expenditure is also very high and incurs high costs.
In particular, some steps for producing the solar module are particularly expensive, such as for example the soldering processes. The material costs for the silver strips 8b for example are likewise very high.